I think you should move on.. maybe there is another girl that likes you and is better for you and has always been there.
just look for another one..there are plenty fish in the sea.
i know it...
watch how they act with their other friends if they treat with a little more respect or when they mess with their hair when they talk to you you will know they like you can also see it in their eyes...
If you really want to get her try all your might to impress her. Maybe catch her eye every now and again, or maybe start sending her love notes from her 'secret admirer'. Try all things that might...
Treat her nicely, even if she isn't being nice to you but it is important to remember that you can't make anyone like you. They either do or they don't.